Young says she should have been offered light-duty work because some UPS workers were.

The Atlanta-based package delivery company says it will voluntarily offer pregnant women light duty starting in January. But the company contends it complied with the law in Young's case.

The question at the Supreme Court is whether UPS was required to accommodate Young, 42, because it gave temporary assignments to some workers, including those who were injured on the job or had a condition that was covered by the Americans With Disabilities Act.

More than 120 Democrats are backing legislation that would change federal law to make explicit the requirement to accommodate pregnant women.